l1: avoid spam calling L1 RPC subscription (#1918)

* Add retry logic for retrieving L1 finalised height

* Sanitize eth_getBlockByNumber unmarshal method

* l1: add EthSubscriber test

l1/eth_subscriber.go

@@ -2,15 +2,15 @@ package l1
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"math/big"
-	"strconv"
-	"strings"
 	"time"
 
 	"github.com/NethermindEth/juno/l1/contract"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
@@ -54,28 +54,21 @@ func (s *EthSubscriber) ChainID(ctx context.Context) (*big.Int, error) {
 }
 
 func (s *EthSubscriber) FinalisedHeight(ctx context.Context) (uint64, error) {
-	finalisedBlock := make(map[string]any, 0)
-	if err := s.client.CallContext(ctx, &finalisedBlock, "eth_getBlockByNumber", "finalized", false); err != nil { //nolint:misspell
+	var raw json.RawMessage
+	if err := s.client.CallContext(ctx, &raw, "eth_getBlockByNumber", "finalized", false); err != nil { //nolint:misspell
 		return 0, fmt.Errorf("get finalised Ethereum block: %w", err)
 	}
 
-	number, ok := finalisedBlock["number"]
-	if !ok {
-		return 0, fmt.Errorf("number field not present in Ethereum block")
+	var head *types.Header
+	if err := json.Unmarshal(raw, &head); err != nil {
+		return 0, err
 	}
 
-	numberString, ok := number.(string)
-	if !ok {
-		return 0, fmt.Errorf("block number is not a string: %v", number)
+	if head == nil {
+		return 0, fmt.Errorf("finalised block not found")
 	}
 
-	numberString = strings.TrimPrefix(numberString, "0x")
-	numberUint, err := strconv.ParseUint(numberString, 16, 64)
-	if err != nil {
-		return 0, fmt.Errorf("parse block number: %s", numberString)
-	}
-
-	return numberUint, nil
+	return head.Number.Uint64(), nil
 }
 
 func (s *EthSubscriber) Close() {

l1/l1.go

@@ -178,6 +178,7 @@ func (c *Client) finalisedHeight(ctx context.Context) uint64 {
 				return finalisedHeight
 			}
 			c.log.Debugw("Failed to retrieve L1 finalised height, retrying...", "error", err)
+			time.Sleep(c.resubscribeDelay)
 		}
 	}
 }

l1/l1_test.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"errors"
 	"math/big"
+	"net"
+	"net/http"
 	"testing"
 	"time"
 
@@ -15,6 +17,9 @@ import (
 	"github.com/NethermindEth/juno/l1/contract"
 	"github.com/NethermindEth/juno/mocks"
 	"github.com/NethermindEth/juno/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/mock/gomock"
 )
@@ -154,3 +159,101 @@ func TestEventListener(t *testing.T) {
 		StateRoot: new(felt.Felt),
 	}, got)
 }
+
+func newTestL1Client(service service) *rpc.Server {
+	server := rpc.NewServer()
+	if err := server.RegisterName("eth", service); err != nil {
+		panic(err)
+	}
+	return server
+}
+
+type service interface {
+	GetBlockByNumber(ctx context.Context, number string, fullTx bool) (interface{}, error)
+}
+
+type testService struct{}
+
+func (testService) GetBlockByNumber(ctx context.Context, number string, fullTx bool) (interface{}, error) {
+	blockHeight := big.NewInt(100)
+	return types.Header{
+		ParentHash:  common.Hash{},
+		UncleHash:   common.Hash{},
+		Root:        common.Hash{},
+		TxHash:      common.Hash{},
+		ReceiptHash: common.Hash{},
+		Bloom:       types.Bloom{},
+		Difficulty:  big.NewInt(0),
+		Number:      blockHeight,
+		GasLimit:    0,
+		GasUsed:     0,
+		Time:        0,
+		Extra:       []byte{},
+	}, nil
+}
+
+type testEmptyService struct{}
+
+func (testEmptyService) GetBlockByNumber(ctx context.Context, number string, fullTx bool) (interface{}, error) {
+	return nil, nil
+}
+
+type testFaultyService struct{}
+
+func (testFaultyService) GetBlockByNumber(ctx context.Context, number string, fullTx bool) (interface{}, error) {
+	return uint(0), nil
+}
+
+func TestEthSubscriber_FinalisedHeight(t *testing.T) {
+	tests := map[string]struct {
+		service        service
+		expectedHeight uint64
+		expectedError  bool
+	}{
+		"testService": {
+			service:        testService{},
+			expectedHeight: 100,
+			expectedError:  false,
+		},
+		"testEmptyService": {
+			service:        testEmptyService{},
+			expectedHeight: 0,
+			expectedError:  true,
+		},
+		"testFaultyService": {
+			service:        testFaultyService{},
+			expectedHeight: 0,
+			expectedError:  true,
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			startServer := func(addr string, service service) (*rpc.Server, net.Listener) {
+				srv := newTestL1Client(service)
+				l, err := net.Listen("tcp", addr)
+				if err != nil {
+					t.Fatal("can't listen:", err)
+				}
+				go func() {
+					_ = http.Serve(l, srv.WebsocketHandler([]string{"*"}))
+				}()
+				return srv, l
+			}
+
+			ctx, cancel := context.WithTimeout(context.Background(), 12*time.Second)
+			defer cancel()
+
+			server, listener := startServer("127.0.0.1:0", test.service)
+			defer server.Stop()
+
+			subscriber, err := l1.NewEthSubscriber("ws://"+listener.Addr().String(), common.Address{})
+			require.NoError(t, err)
+			defer subscriber.Close()
+
+			height, err := subscriber.FinalisedHeight(ctx)
+			require.Equal(t, test.expectedHeight, height)
+			require.Equal(t, test.expectedError, err != nil)
+		})
+	}
+}